(Phys.org) —A team of researchers with representatives from the U.S., Germany and France has found evidence of western Eurasian genes in Khoisan tribes living in southern Africa. This suggests, the researchers conclude in a paper they've had published in Proceedings of the National Academy of Sciences, that a migration from the Middle East back to Africa occurred approximately 3000 years ago.

Scientists believe humans evolved from ancestral primates in Africa several hundred thousand years ago, but it wasn't until approximately 65,000 years ago that they made their way out of Africa and into the Middle East and eventually the rest of the world. Until recently, that migration has been viewed by most scientists as a one-way trip. Gene studies over the past several years has turned that thinking around, however, as its been found that many people in several parts of Africa have European or Asian gene segments in their DNA. In this latest study, the researchers have found evidence of Eurasian genes in tribespeople who were thought to have a purely African ancestry.

The Khoisan tribespeople of today still live much as their ancestors did—they are hunter-gathers who are also pastoralists—they are most familiar to westerners as the people who speak with distinctive clicking noises. Until now, they were believed to have the purest African gene pool due to their thousands of years of isolationist practices.

The team acquired DNA samples from 32 people living in Khoisan tribes in southern Africa—an analysis revealed Eurasian gene segments in all of them. But that wasn't the end of the story. To understand how the gene fragments got into the Khoisan tribespeople, the researchers turned to archeological and linguistic evidence to build a possible time-line of events. In so doing, they've found what they believe to have been a migration back into Africa by people of the Middle East (ancestors of the people that migrated to Europe and Asia) approximately 3000 years ago. Those people made their way to various parts of the continent, including a part of eastern Africa from which the Khoisan tribespeople had migrated south approximately 900 and 1800 years ago.

The researchers found something else—the Khoisan tribespeople also had snippets of Neanderthal DNA in their genes as well—courtesy of their Eurasian heritage.

AbstractThe history of southern Africa involved interactions between indigenous hunter–gatherers and a range of populations that moved into the region. Here we use genome-wide genetic data to show that there are at least two admixture events in the history of Khoisan populations (southern African hunter–gatherers and pastoralists who speak non-Bantu languages with click consonants). One involved populations related to Niger–Congo-speaking African populations, and the other introduced ancestry most closely related to west Eurasian (European or Middle Eastern) populations. We date this latter admixture event to ∼900–1,800 y ago and show that it had the largest demographic impact in Khoisan populations that speak Khoe–Kwadi languages. A similar signal of west Eurasian ancestry is present throughout eastern Africa. In particular, we also find evidence for two admixture events in the history of Kenyan, Tanzanian, and Ethiopian populations, the earlier of which involved populations related to west Eurasians and which we date to ∼2,700–3,300 y ago. We reconstruct the allele frequencies of the putative west Eurasian population in eastern Africa and show that this population is a good proxy for the west Eurasian ancestry in southern Africa. The most parsimonious explanation for these findings is that west Eurasian ancestry entered southern Africa indirectly through eastern Africa.

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They've been doing genetic studies on this group for years and they are somehow just now finding this out? Bolonga! Studies have already shown that this group has 9 DNA markers vs. the usual 6 for normal people indicating that they are the oldest group of people living. That is to say, if they started in Africa, they are purely African.They leave Africa (where they began) for the Middle East, came back some thousand years later and now have "Eurasian ancestry"? What you mean to say is Eurasians have their ancestry.They came first! Eurasians don't have 9 DNA markers as they do.The genetic diversity of mankind began in Africa as evidenced by this group if you look at their varying phenotypical characteristics.A portion of them left and while in Asia further branched off.That's why all across Asia and in Eastern Europe going back to the time of the Greeks you see small groups of black woolly hair peoples who seem so out of place.They are the offshoots of these people. Please be consistent

Believe it or not, you can have both the most ancient diverging genes and more modern ones all mixed together in one body.

Humans in coastal fishing boats have survived journeys of thousands of miles and could have bred with local people where they ended up. If those descendants have beneficial traits either through learned behavior or genetic benefits, they will be more likely to have surviving offspring and pass those genes on. I would imagine people living in the middle east would have a number of different tech developments that would greatly enhance the tribes' overall ability to survive.

Believe it or not, you can have both the most ancient diverging genes and more modern ones all mixed together in one body.

Humans in coastal fishing boats have survived journeys of thousands of miles and could have bred with local people where they ended up. If those descendants have beneficial traits either through learned behavior or genetic benefits, they will be more likely to have surviving offspring and pass those genes on. I would imagine people living in the middle east would have a number of different tech developments that would greatly enhance the tribes' overall ability to survive.

Somebody check for Nubian genes. These folks may have been part of an ancient Nubian group that was south of Egypt but north for a while with Taharqa's forces in the wars of the XXV Dynasty with the Assyrians. When Essarhaden the Assyrian defeated the Nubians finally, they had to retreat to Nubia. It is possible that Essarhaden's forces tried to follow in order to kill them all....such was the way of wars then, defeat and then pogroms. It would have been a natural for the defeated Nubians to make their way south. Inasmuch as other peoples would already be in those territories, then the Nubians had a very long journey over many generations before finally winding up in genetically modified form in then almost empty south Africa. Africa was a hard place to live, with frequent plagues from many causes. Lucky these fellows made it. They did not have time to lighten, but plenty time to re-darken to protect from UV. Take a look at the Nubian features on this man depicted.

The most parsimonious explanation for these findings is that west Eurasian ancestry entered southern Africa indirectly through eastern Africa.

That's only the most parsimonious explanation if you believe in the ridiculous theory of mutation-initiated natural selection. If you believe the experimental evidence, it shows why ecological adaptations make it appear that Neandertal DNA is so widespread that theorists must keep changing their misrepresentations of migrations to make the experimental evidence fit their ridiculous theories.

"the Khoisan tribespeople also had snippets of Neanderthal DNA in their genes as well—courtesy of their Eurasian heritage."

Bummer #1: that may mean the previously seen signal of african introgression from human ancient populations is not indicative of a 4th population besides the eurasian Neanderthal, Denisovan and H. erectus admixture.

@Frank: Frankly, you are making fractal errors, indicating you didn't understood what you read here or before. The lack of consistence is on your part. (Mostly, because this is a new area and initial results will change and even contradict because of early mistakes.)

These africans never exited Africa (read here); of those who did, they are _us_ (read here; but also elsewhere); and your anecdotal but possible phenotype characteristics aren't tied to genome results (read elsewhere; and don't make stuff up).

@scottfos: It was based on anthropology (no evidence of back-migration) but also genomes (most variation in africans indicate undiluted root).

There is nothing very new in this. I point to the 2002 article in Am J Hum Genet. 2002 January; 70(1): 265–268.

"the Ethiopian Y chromosomes that fall into Groups VI, VIII, and IX may be explained by back migrations from Asia. The first observation confirms the ancestral affinity between the Ethiopians and the Khoisan, which has previously been suggested by both archaeological and genetic findings."

They've been doing genetic studies on this group for years and they are somehow just now finding this out? Bolonga!

Can't find what you haven't looked for, and small amounts of admixture are hard to detect.

Studies have already shown that this group has 9 DNA markers vs. the usual 6 for normal people indicating that they are the oldest group of people living. That is to say, if they started in Africa, they are purely African.

Yes, the Khoisan have the earliest divergence date and are absolutely the oldest group of people living. *But*, we're now finding out that they occasionally interbred with people who returned from Europe to Africa.

The fact that some people returned from Europe to Africa isn't a surprise; we knew that from finding R1b in Africa.

@Osiris1: How are you defining "Nubian"? There were pretty big Khoisan populations in Ethiopia in historic times, which later migrated south - that's probably how these genes got to southern Africa.

It's been established irrefutably through DNA analysis that the closest living relatives to King Tut and his family are now to be found in northwestern Europe in the Scandinavian countries FYI. More importantly, It is also established through analysis of the tracing of the evolution of the Y chromosome (which remains virtually unaltered throughout the history of mankind) that all men have a common ancestor, which is in keeping with the first man creation theory, wherein Ninhursanga (a female god of the Anunaki of Nibiru) creates Adam (after many failed attempts - it seems the gods are human after all) by combining their Nibiruan DNA with the DNA of a Neanderthal. They did this to create an intelligent worker class to mine gold in South Africa because the Anunaki workers were tired of the toil, and they revolted. The presence of those DNA markers in these Africans is not so surprising, then. DON'T LAUGH! This actually happened! Those gods are indeed crazy, man.

So the Bushmen are white? The Bantu people should demand immediate reparations for slavery and colonialism etc.

I dunno, but, His Imperial Majesty Haile Selassie I, Conquering Lion of the Tribe of Judah, King of Kings of Ethiopia, Elect of God, was Caucasian, or so he said. And who are we to gainsay His Majesty?

Agreed, I should have reparations for slavery and colonialism in compensation for the Roman deprivations in Britannia and Caledonia.

I'm 99% certain that the Namibian San pictured in the photo is the guy who played Xi in "The from the same tribe... Either this photo is 30 years old, or members of this tribe have more than just shared characteristics- I swear they look exactly alike! ;) Haven't thought of that movie in years. Good Stuff!

In central Tanzania there is an area where people of different origins live along side each other. There are herders like the Iraqw people who speak a language of the Southern Cushitic group which is part of the Afro-Asiatic family of languages. This family includes Hebrew and Arabic. There are people who speak languages of the Khoisan family such as the hunter-gatherer Hadza and the herding Sandawe. There are also herders who speak languages of the Nilo-Saharan family.

It seems that people in south west Asia spread into northern Africa bringing the Afro-Asiatic languages with them. Some spread to Ethiopia and some of these moved south along the eastern branch of the Rift Valley to central Tanzania. They were in contact with the indigenous Khoisan-speaking hunter-gatherers, some of whom adopted herding from them.

These Khoisan-speaking herders were the ancestors of both the Sandawe people and the Khoi-khoi people who eventually made their way from eastern Africa to southern Africa.

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